2015-01-04 19:02 GMT+03:00 <sftf-misc@xxxxxxx>:
Hello!
Question generally to (libpq) developers.
According to http://www.postgresql.org/docs/9.4/static/libpq-async.html:
"PQsendQuery cannot be called again (on the same connection) until PQgetResult
has returned a null pointer, indicating that the command is done."
As I guess this is also true for all PQsend* functions, like PQsendQueryPrepared,
although this is not explicitly stated in the documentation.
So question is why this limitaion exists?
Because it's violates the protocol -- sending messages like Parse or Bind to the backend
until the CommandComplete or ErrorResponse consumed by the frontend is wrong.
Why PQgetResult(PGconn *conn) operates on connection,
and not on some unique handler that each "PQsend*" could return.
It does not make sense because of the message flow described by the protocol.
Is it limitaion of libpq or architecture of postgresql backend or backend-frontend protocol?
PS. If you need pipelining take a look at the thread "libpq pipelining" in hackers-.
// Dmitry.
